1. Field of the Invention
This invention relates to a motor control system and particularly to a system for controlling the acceleration of a d-c motor through a fixed angle of rotation.
While not necessarily limited thereto this invention has particular application to a control system for motors which drive a print element of the type used for endorsing moving unit record documents.
2. Description of the Prior Art
In document handling machines, unit record documents such as checks or the like are endorsed by a rotatable type element driven by a motor. The type element is usually in the form of a type segment which is rotated by the motor through a fixed angle usually from a predetermined initial position at rest to a predetermined velocity which approximates the speed of travel of the document to be endorsed. For good legibility, as well as precise location of the endorsement onto the check, the acceleration of the drive motor should be very precisely controlled. Various systems for controlling the acceleration of the motor have been provided such as shown on pages 1918 - 1919 of the IBM Technical Disclosure Bulletin, Vol. 14, No. 6, dated November 1971. Prior systems while being capable of accurate acceleration of the d-c motor have certain limitations under some operating conditions. For example, should the velocity of the document to be endorsed be substantially changed such as when the document handling machine is in the process of starting up or shutting down, then the location of the endorsement and its legibility could be seriously disturbed unless the motor is capable of being controlled to meet the changing velocity conditions.